In Vitro Embryos of Romosinuano and Tropical Milking Cattle during Three Seasons in Veracruz, Mexico.

One of the main factors that influences the fertility of cattle in grazing systems in hot tropical climates is heat stress. The objective of this study was to evaluate the effect of season, breed, hormonal and physiological condition on the quantity and quality of cumulus-oocyte complexes (COCs) and embryos produced in vitro, from Romosinuano (RM) and Tropical Milking (TM) donors. Three ovum pick-up and in vitro fertilization (OPU-IVF) were performed, one per season: hot dry (HD; 10, 10), hot humid (HH; 9, 9) and fresh dry (FD; 7, 10) in RM and LT donors. Serum levels of cortisol, insulin and glucose were measured, in addition to heart rate (HR), respiratory rate (RR) and rectal temperature (RT). Effect of season x genotype interaction (p ≤ 0.05) was observed in all COC variables and only in cleavage embryos (CLI) (p ≤ 0.05). Body weight (BW) affected all COC variables (p ≤ 0.01), except unviable (UNV) although affected degenerated embryos (DEG) (p ≤ 0.01) and total blastocysts (BLAST) (p ≤ 0.01). Cow age only affected viable COCs (VIAB) (p ≤ 0.05), code one blastocysts (BC1) and BLAST (p ≤ 0.01). Cortisol affected total COCs (COCsT), VIAB and total matured in vitro (TMIV) (p ≤ 0.01), as well as CLI, BC1 (p ≤ 0.01) and BLAST (p ≤ 0.05). Insulin affected COCsT (p ≤ 0.01), UNV (p ≤ 0.05), denuded oocytes (DE) (p ≤ 0.01), BC1 and code two blastocysts (BC2) (p ≤ 0.01). Glucose affected all COC variables (p ≤ 0.01), except UNV and all embryo variables except BC2. HR affected COCsT, DE, TMIV (p ≤ 0.01), CLI, BLAST and DEG (p ≤ 0.05). RR affected COCsT, UNV, VIAB, CLI (p ≤ 0.05), BC1, BLAST and DEG (p ≤ 0.01). RT only affected DE, VIAB (p ≤ 0.01) and BLAST (p ≤ 0.05). The seasonal climatic year variation of Veracruz and changes in physiological and hormonal variables have diverse effects on the cumulus-oocyte complexes and embryos produced by RM and TM donors.

Growth performance, carcass, and meat quality traits of Tropical Milking criollo bulls fed with two energy-level diets.

The aim of this study was to determine the effect of two energy-level diets on the beef performance of Tropical Milking criollo bulls grouped by weight and age in three periods: initial, middle, and final. Evidence on intensive beef production from Tropical Milking criollo cattle breeds are unknown, and productive alternatives for dairy producers in the hot tropics are needed. Bulls were fed in each period with low (LE, 2.2 Mcal ME/kg DM) and high (HE, 2.9 Mcal ME/kg DM) energy diets and content phase feeding protein of 14.5, 12.0, and 10.3%, respectively. For each period, ten bulls were randomly assigned to diets. In all periods, growth performance for final body weight, average daily gain, feed intake, and feed conversion were all superior in HE (p ≤ 0.05). For the final period, slaughter body, hot and cold carcass weights, and dressing were also superior in HE (p ≤ 0.05); for meat quality traits, differences were observed in muscles Longissimus dorsi, Semimembranosus, Infraspinatus, and Serratus ventralis for pH and tenderness (p ≤ 0.05), although not for diets. For color L*, a*, and b* system, neither diet nor muscle had effect on L* (p > 0.05); however, the diet-muscle interaction was significant for a* (p ≤ 0.05), and only muscle effect was detected for b* (p ≤ 0.05). Tropical Milking bulls responded positively to a high-energy diet, despite not being a beef breed.

Relation of the maximum temperature and relative humidity close to the insemination with the tropical milking criollo heifer's gestation in three seasons.

The high climatic variability of hot climates of the intertropical zone reduces cattle fertility. In dairy cows in temperates zones, the THI has been used to evaluate the temperature and relative humidity (RH) joint effect in reproduction, but its use is not recommended in all geographic zones; in hot climates, the maximum temperature (Tmax) can provide more convenient information than THI. The objective of this study was to determine the artificial insemination (AI) service seasons and their joint effect with the maximum temperature and relative humidity of the previous seven days, the service day, and posterior seven days to the AI in the tropical milking criollo (LT) heifer's gestation. Climatic data was used to define three seasons: hot-dry (HD), hot-humid (HH), and fresh-dry (FD), and 313 artificial insemination services from 176 heifers were analyzed over fourteen years. The seasons were determined by cluster analysis. Gestation at first service (GF) was analyzed with a logistic regression model and global gestation (GG) with a mixed linear generalized model. The Tmax of previous seven days insemination [Formula: see text] - 0.20 ± 0.09 (p ≤ 0.02) in HD (p ≤ 0.02) and RH of seven days posterior insemination [Formula: see text]= - 0.08 ± 0.04 (p ≤ 0.04) in HD (p ≤ 0.01) affected GF. No effect of the Tmax and RH on the service day was observed (p > 0.05). The highest GG probabilities were higher than 0.70 in HH and FD, making those seasons the most suitable for inseminating LT heifers.

Kappa-casein genotyping in tropical milking Criollo and its association to milk production and composition.

Caseins are abundant proteins in milk and found in four types (αS1, αS2, ß, and κ). There is substantial variation in the allelic and genotypic frequencies of the κ-casein gene in different cattle breeds, although the tropical milking Criollo (TMC) has not yet been investigated. The aim was to determine the allelic and genotypic frequencies in the κ-casein gene for two alleles (A and B) in TMC and further investigate its association to milk production and composition. A total of 180 TMC females were genotyped from blood samples. κ-Casein genotyping was performed using restriction fragment length polymorphism (RFLP) after polymerase chain reaction (PCR)-based amplification of genomic DNA. Allele frequencies were 0.39 for A-allele and 0.61 for B-allele (P < 0.05). Genotype frequencies were 0.09 (AA), 0.60 (AB), and 0.31 (BB) (P < 0.05). The κ-casein genotype in TMC cows did not affect milk yield or composition. In sum, the TMC has high frequencies of the B-allele and AB/BB genotypes, although there are no association of such genotypes and milk traits.

Genetic variability of Tropical Milking Criollo cattle of Mexico estimated from genealogy information / Variabilidad genética de la raza bovina criolla Lechero Tropical de México estimada a partir de información genealógica / Variabilidade genética da raça bovina crioula Leiteiro Tropical do México estimada a partir de informação genealógica

Abstract Background: Genetic variability of populations is essential for their genetic conservation and improvement, and genealogy analysis is a useful tool to estimate it. Objective: To determine genetic variability and inbreeding levels in Tropical Milking Criollo (LT). Methods: This study analyzed the genealogy of LT using the ENDOG software. Registration certificates of 3,427 LT animals born between 1945 and 2013, and from 608 born between 1950 and 2013 were used. Two populations were defined: the first one with all registered animals (PLT), and the second with nucleus animals (PCP). Results: Estimates for PLT and PCP were: founders 890, 114; ancestors 855, 102; effective founders 111, 43; effective ancestors 72, 26, and effective population size 68.1 and 64.6, respectively. Inbreeding coefficients were 4.32 and 3.48% for the highest genetic integrity index; and the average relatedness (AR) coefficients were 1.19 and 5.55 for PLT and PCP, respectively. Genealogy depth was shallow in both populations, with full equivalent generations of 2.00 and 3.53. Global generation intervals were about seven years. Conclusions: The LT population is not endangered and its genetic improvement program should continue.

Resumen Antecedentes: la variabilidad genética de las poblaciones es esencial para su conservación y mejora genética, y el análisis de genealogía es útil para estimarla. Objetivo: determinar la variabilidad genética y los niveles de consanguinidad en la raza criolla Lechero Tropical (LT). Métodos: el estudio analizó la genealogía de la raza criolla LT con el programa ENDOG v4.8. Se utilizaron 3.427 registros de animales LT nacidos entre 1945 y 2013, y de 608 nacidos entre 1950 y 2013. Se definieron dos poblaciones, una que incluye todos los animales registrados (PLT) y otra solamente con los animales provenientes del núcleo genético (PCP). Resultados: en la PLT y PCP se estimaron animales fundadores 890, 114; ancestros 855, 102; número efectivo de fundadores 111, 43; número efectivo de ancestros 72, 26, y tamaño efectivo de población 68,1, 64,6, respectivamente. Para la categoría más alta de índice de integridad genética, los coeficientes de consanguinidad fueron 4,32 y 3,48%; y el coeficiente medio de relación global (AR) fue 1,19 y 5,55 para PLT y PCP, respectivamente. La profundidad de la genealogía en ambas poblaciones fue superficial con generaciones completas equivalentes de 2,00 y 3,53. Los intervalos generacionales globales fueron cercanos a siete años. Conclusiones: la población LT no se encuentra en riesgo de extinción y puede continuar con su programa de mejora genética.

Resumo Antecedentes: a variabilidade genética das populações é essencial para sua conservação e melhora genética e a análise da genealogia é útil para estimá-la. Objetivo: determinar a variabilidade genética e os níveis de consanguinidade na raça crioula Leiteiro Tropical (LT). Métodos: o estudo analisou a genealogia da raça crioula LT com o programa ENDOG v4.8. Foram utilizaram 3.427 registros de animais LT nascidos de 1945 a 2013, e de 608 nascidos entre 1950 e 2013. Foram definidas duas populações, uma que inclui todos os animais registrados (PLT) e outra somente com os animais provenientes do núcleo genético (PCP). Resultados: na PLT e PCP foram estimados animais fundadores 890, 114; ascendentes 855, 102; número efetivo de fundadores 111, 43; número efetivo de ascendentes 72, 26 e tamanho efetivo da população 68,1, 64.6, respectivamente. Para a categoria mais alta de índice de integridade genética os coeficientes de consanguinidade foram 4,32 e 3,48%; o coeficiente médio da relação global (AR) foi 1,19 e 5,55 para PLT e PCP, respectivamente. A profundidade da genealogia em ambas populações foi superficial com gerações completas equivalentes de 2,00 e 3,53. Os intervalos geracionais globais foram próximos a sete anos. Conclusões: a população LT não se encontra em risco de extinção e pode continuar com seu programa de melhoria genética.